new RegExp. test

Question

http://stackoverflow.com/questions/3861970/regexpression-test
I have posted a problem in the above link

based on that i have done like bellow That too is error

var regExpression=new RegExp("^([a-zA-Z0-9_\-\.]+)$");
alert (regExpression.test("11aa"));

Answer 1

You need to escape your \ since you're declaring it with a string, like this:

var regExpression=new RegExp("^([a-zA-Z0-9_\\-\\.]+)$"); 
                                           ^  ^ add these

You can test it here.

Answer 2

You can also use the literal RegExp syntax /…/:

var regExpression = /^([a-zA-Z0-9_\-\.]+)$/;

By the way: The . does not need to be escaped in character classes anyway. And if you put the range operator at the begin or the end of the character class or immediately after a character range, it doesn’t need to be escaped either:

var regExpression = /^([a-zA-Z0-9_.-]+)$/;